Kobolds and Catacombs Dungeon Run: It's Not Broken And Blizzard Doesn't Hate You (A Guide)

If you research what makes up the greatest proportion of traffic on the Internet, the list goes like this:

1. Spam (70%)
2. Porn (13.5%)
3. Complaining (9.83%)

Thus it wasn't much of a shock to go to the Hearthstone forums and find people griping about the new Dungeon Run being unbalanced, broken, etc., and that certain classes are terrible. That being said, it was still a small surprise to see so many different complaints in such a small space, most of which were then followed by replies that said nothing was broken and all these other people had managed beating Boss X or clearing the dungeon with Class Y with no problem. I stayed on the edge of the whimpering black hole, careful not to get sucked into the vortex, and then went to Google to see if anyone had written a guide.

Much to my actual surprise, there isn't much. Metabomb has a guide that was written early and hasn't been fully completed yet, and Icy Veins has a rundown of how the mode plays with a much more helpful list of bosses (in the order of potential appearance rather than alphabetical). So, here in my infinitesimally small corner of the web, I'll use what they've written and fill in some gaps. I'm also keeping it all on one page rather than the way Icy Veins makes you click a link for every separate thing. Each boss link leads to its Gamepedia deck list, if you want to see exactly what you're up against.

If you see any issues, leave a comment.

Note: The farther you get into the run, the more variable the right strategy becomes. This is just designed to be a quick overview of each boss with some broadly applicable approaches. However, apart from the final bosses, every boss should be beatable by every class with most types of decks unless you get particularly unlucky in some fashion. If you keep getting unlucky, consider the possibility it's not all luck.

Building Your Deck

Because I have other things to do, I'm not going to break down every class, much less every bucket. The randomness of the offered cards makes ultra-specific guidance difficult or impossible, and once you're comfortable with the mode you won't need it anyway. Rather, here are some basic tips:

• Synergy > individually powerful cards. This means both synergy within the deck and the deck's synergy with your treasures. If you get a good bucket right off the bat, look to take the same bucket type when it shows up again. Don't do it mindlessly, though; you still need your deck to have overall strength, ie. a good curve and not an excessive number of spells with minimal board presence. And some buckets that technically aren't part of the same group will still offer cards that synergize well with what you have.
• Play around your early treasures if possible. Very few treasures (see below) are good with any deck, and even those can have their value maximized if you build your deck to exploit them. The Captured Flag, for example, gains massive benefits from a zoo-type deck, especially minions that produce other minions (e.g. Fire Fly), or just being in a shaman or paladin decks. Be forewarned that if you take more situational treasures early, like Totem of the Dead or Battle Totem, you may not be offered the cards to take advantage of them.
• You're going to need some big minions. Too many things in the dungeon can wipe a small board. If you get the Captured Flag, your flexibility in this respect increases dramatically.
• Most deck archetypes can succeed, and they can all fail. Here are a few that can do especially well:
• Jade Druid
• Deathrattle Hunter
• Unique Priest (don't get a double of anything!)
• Jade Rogue
• Anything that can maintain board presence regardless of what the enemy does

The Dungeon

Level One:

• Bink the Burglar, Giant Rat, Wee Whelp. Just rush them down. There's no real way for them to win if you're trying. The rat is the only one that can surprise you, if it gets out a handful of rats and then throws down a Timber Wolf, but in basically all cases you can throw everything at the face with only the most obvious trades and not be in danger.

Level Two and Three (except for Candlebeard, all the level two bosses also appear on level three with the same hero powers and presumably the same decks):

• Candlebeard. His charge effect isn't limited like in the regular game; minions can go face right away. He also has Pit Vipers and Stoneskin Basilisks that can take something out immediately. However, it costs a mana for him to give minions charge, so you won't be suffering massive face damage right from the start. If you take a high-mana bucket first and get a bad draw, just do whatever you can to survive until you stabilize. Any decent draw should be an easy win.

• Elder Brandlemar. There are three basic approaches—don't cast a spell after turn two, only cast a spell to trigger his counterspell so you can cast another on the same turn, or cast something to trigger his counterspell so he spends two mana on another one the next turn rather than playing something to the board. Base your approach on what you draw.

• Frostfur. He freezes a minion for two mana, so go wide (more minions) rather than have one big thing on the board. Taunts are fantastic. Trading is more important here; he doesn't have board wipes, so go ahead and leave yourself with some 1 hp minions if it means he has more targets to deal with.

• Graves the Cleric. His hero power is useless early; healing all minions for two doesn't do much with what he plays the first couple of turns apart from Northshire Cleric. On turn three he can drop an Injured Blademaster and heal it so you're staring at a 4/5. His health is low enough that if you have minions out but no efficient way to remove the Blademaster, you can generally keep playing stuff and go face to beat him before he out-values you. Almost every deck should have enough go-face capacity to aggro out a win.

• Overseer Mogark. Plays a lot of eggs in order to use his Inner Rage hero power on them so they kill something and pop out something else nasty, and sometimes Rampage on top of that. If you've come across any silences, just one on a Nerubian Egg can break his whole plan for long enough that you smash him. Unless you have a way to deal with the deathrattle effects, rush him down.

• Pathmaker Hamm. So many bombs. He only hits any given target once, so there's no need to play out a 1/1 on the first turn (e.g. Jade Idol) that will get killed for no reason. With the Mad Bombers, though, you need to throw down as many minions as you can so that your board only gets damaged rather than completely wiped. Certain passives make this much easier, namely the +1/+1 to all minions, or the Justicar's Ring on shaman or paladin. Know when to trade a damaged minion into one of his and you can otherwise brute force this down.

• Seriona. The most dangerous level two boss. Her hero power is the weakest, but she has a dragon deck with the new 4-cost dragon that Hellfires your board. If the game goes late enough, she also has the new 4/12 taunt dragon, which many decks are not going to be equipped to deal with. If you have enough minions with 4+ health, you shouldn't have much to worry about, but certain decks will be vulnerable to her cards.

Level Four Only:

• A.F. Kay: Does nothing until turn 6. On turn 6, she plays Boots of Haste and fills the board with 8/8s. She has no taunts or charge minions, so you'll have your turn 7 to finish her off before she gets to attack, but she can play Ragnaros the Lightlord for some healing. After that, most decks without sufficient taunts or removal will just die, but most decks are capable of winning by that point.

• Brimstone Warden: The obvious thing here is to not let him get five mana crystals. However, the sooner you can kill his statues the better, since that will limit what else he can play against you. Hard removal is amazing here, although Mulch is playing with fire a little bit. Several minions work better than fewer, larger ones due to his poison creatures and traps. He'll also play more statues if you clear most of the ones that start on the board, but in general the game should end before you see more than one or two extras.

• Fungalmancer Flurgl: Clear everything early, go face if you get so far ahead that he can't stop you. If he takes over the board, the hero power will destroy you without an AOE clear. Even if, for example, you battle to turn eight and then Twisting Nether, he can follow that with six mana of minions and a hero power. Not hard unless you draw super heavy, but this is one of those bosses that gives you a reason to make sure your deck curves well.

• Kraxx: Set up your board with the awareness everything will take one damage at the start of his turn and it's otherwise a fairly straightforward game. He builds a lot of armor, has cards that make use of lots of armor, and holds a couple of 5/9 taunts, but as long as you don't play into his hero power or his Executes you shouldn't have too much trouble.

Level Four and Five:

• Battlecrier Jin'zo: Abuse his double battlecry effect if you have the cards to do it. Beware the effect if you have negative battlecries (e.g. Doomguard). Low health minions are particularly vulnerable to effects like double Ravaging Ghoul. He also has cards like Bomb Lobber and Bomb Squad, so balancing the number of minions you have with the health of those minions is wise. Be aware he has Blubber Barons which can come out massive if he's held them from the beginning of the game.

• Blackseed: Get minions out and do everything you can to control the board. If he plays something like Dopplegangster, it's doubly important you wipe it the next turn—bad enough for him to upgrade one of those 5-costs, you don't need him doing it again. If you can't kill everything he has, your next priority is to remove anything that could kill something of yours and then be evolved, which effectively heals it. If he's allowed to trade and evolve the same creature over and over, you're in trouble.
  
  When he plays Living Mana, leave the crystals up if you can; he doesn't evolve them and it leaves him with no mana for the next turn while he trades the crystals into your minions. If you have stealthed minions and can survive the Living Mana crystals attacking your face, the fight is easy.

• Elder Jari: Praise RNGesus if you get him. Treat it like a normal game; his deck and hero power are built around his survival, so make the best trades you can to stay on top of the board. He can at least theoretically ramp into Ysera, Kun, and Ultimate Infestation, so if the game goes late have something ready to deal with those eventualities.

• Gutmook: Plays a lot of troggs, so you'll often have more reasons not to cast a spell than the fear of spawning a Tunnel Trogg, and he plays things like King Mukla that give you cheap spells which will help him far more than you. If you can control all the ways in which he would benefit from your spells, though, the fight's pretty easy. If you can't, and you're running a spell-heavy deck, this one might hurt. Having the +3 spell damage passive can actually help a reasonable amount if you have enough spells that benefit from it, but in general this one comes down to the quality of the minions you draw. 

• Lyris the Wild Mage: She's slightly annoying until the Flamewakers come out, at which point she can become monstrous. Everything in this match needs to be focused on removing Flamewakers. Fortunately, she may be the most predictable boss in the game. If she has three mana, she'll play a Flamewaker; if she has less than three but more than zero, she'll play Arcane Missiles if she has one in her hand, and her hero power if she doesn't.
  
  This means that if it's turn six, she'll play two Flamewakers and no spells, regardless of circumstances. Thus it's sometimes correct to wait on playing minions that could die to Arcane Missiles, especially high attack/low health minions, so that they're in position to take out Flamewakers instead. If all she has to work with is Arcane Missiles and the Flamewakers she played to the board that turn, you should beat her well before she becomes a problem.

• Mushhuckster Max: His hero power is Kazakus potions. Try to play your deck to the best of its potential, because you don't know what he's going to throw at you. If you're lucky, his potions won't do much and he'll let his hand fill so that his potion autocast doesn't actually make anything. Usually beatable without doing anything special, but if you go all-in and leave yourself vulnerable to a Kazakus potion (ie. a large board of low health minions) you might get punished.

• Russell the Bard: If you don't play anything with two or less attack, his hero power is worthless. Either leave them in your hand or wait until you can play several at once so you still have most of them once he steals one. Unless your entire deck is based on these types of minions, this is generally enough to win.

• Spiritspeaker Azun: Jin'zo's opposite. If you have the stealthed minions passive, this fight is trivial, as Azun can't trigger his deathrattles without running his minions into yours. If you don't have stealthed minions, do your best to avoid letting him have good trades—you don't need him getting the better of a trade and then a good double deathrattle on top of it. 

• Thaddock the Thief: Quest rogue. If she played intelligently, she might be end boss-level difficult. Because of that, if she gets the perfect draw, it's not impossible for this to be an extremely difficult fight. But she doesn't play intelligently. She spends all her mana every turn, even if that means playing the minion she's using for the quest with no mana left to bring it back into her hand with her hero power. Pay attention to what she's returning and re-playing and kill it if she lets it stick to the board. This can be annoying if it's Glacial Shard, but even in that case you should get your chance.  If she doesn't finish the quest, you win.
  
  If she does complete the quest, your fate largely depends on how close you are to winning at that time (barring something like the Scepter of Summoning that may let you fight back against the 5/5 horde). Should you get unlucky and she pops the quest within a couple of turns, try to burn her down before she has the mana to cast the quest reward, and keep her board clear going into her turn five so nothing automatically becomes a 5/5. After that, just try to keep threatening minions out; she plays very inefficiently, removing minions when going pure aggro would kill you within a couple of turns, and even returning her minions to her hand before attacking with them.

• Waxmancer Sturmi: He has mostly deathrattle minions, so the 1/1 copies he makes of his own stuff can be annoying. Try to beat him before those deathrattles become too much of a hassle. Avoid playing anything he can abuse unless it would still be to your advantage overall.

• Whompwhisker: Not everything in his deck is massive, although some games it seems that way. The biggest headache is if he recruits the 4/12 taunt dragon early. If you have a hard removal card, save it for as long as you can unless you have others to rely on. In general this is a burn fight; if he recruits smaller stuff, you need to win before the really dangerous minions come out, and if he recruits the big things immediately, you often won't have a good way to deal with them. On top of that, if you manage a massive board advantage, he can cast Brawl. Don't overload on big minions in fear of seeing this guy, but if you do happen to face him, it's good to have a few.

Level Six Only:

• George and Karl: At first, your goal is to keep Divine Shield off of the minions, as George will play a monster Blood Knight given the opportunity. A common opening is Lost In The Jungle (two 1/1s), hero power (divine shields on both), then a 9/9 blood Knight. Cards that buff Silver Hand Recruits are also in their deck, so ignoring an army of 1/1s is not advised. If you kill George, Karl jumps in with a fresh 30 HP and a new hero power (two 1/1 recruits, same as the upgraded paladin power), so don't finish off George until you're ready for Karl. Just hold down the board and you should be fine.

• Gnosh the Greatworm: His hero power is scary until you realize he'll eat his own minions. At some point you may be able to get enough minions on the board so that it doesn't matter if he eats one of yours, but in general you want to abuse his use of berserkers so that he clears his own board and you have free reign to beat his ass.

• Ixlid: The cry of a thousand bitter gamers rises up from this one. If a reason exists to have smaller minions in your deck, it's the mere possibility of facing Ixlid. The spores from his hero power need to be removed; early on it's probably enough to make sure you have a taunt up, since the hero power is automatic, but it's much better not to take the risk of something removing your taunt and letting the spore insta-kill you.
  
  A deck that curves well and mulligans hard for early game cards will usually be fine, but it's possible to just get screwed no matter what you do. If it happens every time you face him, though, you might want to look more carefully at how you build your decks or choose your passives/treasures.

• Tad: Every turn, Tad pulls a random minion from his deck. That's all he does. He has no hand of cards and doesn't draw any. It's a walkover fight if you just try to beat him, but if you don't touch him and let him live until he's summoned his whole deck, he summons a Sunken Chest that puts Tad's Pole in your dungeon deck. He summons the deck in mana cost order; kill the Starving Crab when it shows up so it doesn't damage Tad if you want the prize.

• Treasure Vault (no deck): This is the one boss I haven't seen, but apparently it's just a room of treasure chests that you have five turns to kill for loot to help the last two fights of your run.

Level Seven Only:

• Chronomancer Inara: Her hero power looks insane at a glance, but keep in mind it takes ten mana to use. She can't play anything else on the turn, so she's destroying three mana crystals in order to get an extra attack with whatever she has on the board. If you clear her board before any turn where she'll have ten mana, the hero power is effectively wasted.
  
  Much more dangerous is the Astral Portal that brings out a random legendary for one mana; lots of legendary minions are crap, but if she has that card early and gets one that isn't crap, it's difficult or impossible to deal with. All you can do is make sure any minions like the Archmage's Apprentice that amplify the potential of her portals are cleared immediately.

• Jeeru: Jeeru takes advantage of the fact that so many other bosses are troublesome for zoo-type decks with lots of cheap cards. Since most decks are going to have plenty of more costly cards, it's extremely difficult to make use of the card draw she's giving you without burning some. Given her hero power, you'd expect that she has a ton of cheap stuff, but she winds up burning a ton of cards herself and goes to fatigue as quickly as you do. The Arcane Golems and Dirty Rats in her deck also help you quite a bit. She punishes super-heavy decks and terrible draws, but just play as many cards as you can each turn and it should be enough.

• The Mothergloop: Take advantage of the fact her hand buff hero power is on autocast and limits how much mana she can spend on minions each turn and bash her face as often as possible, because you will not be able to clear her minions without hard removal or hyper-buffed minions. Try to save that type of removal for taunts boosted taunts (just Saronite Chain Gang, thankfully) or when she'll have lethal without a clear. Some decks will manage, some won't. Very few will have an easy time.

• Trapped Room: Probably the most frustrating room you can come across, and definitely the one with the least apparent correct approach. If you have a way to routinely remove 3/3 sawblades, you might not have much of a problem. However, because the traps are random, and the real danger is usually the sawblade that spawns as opposed to the secret itself, it's difficult to do anything without putting yourself in massive danger.
  
  The only relatively safe approach is for a hunter to use their hero power every turn; unless one of the secrets is Dart Trap, the hunter can kill the room before the Secretkeepers the room has in its deck can kill the hunter (since they never get buffed). However, if the room plays an Ethereal Arcanist, the Arcanist has to die, and playing something that can kill it can set off traps which drag you into the mire.
  
  More broadly, try not to set off more than one or two traps on a turn unless you can clear them, or spam everything if the room has a full board that prevents the sawblades from spawning. And if you manage to find something that doesn't set off a trap (e.g. playing a minion), do that as much as you can before doing something else that can set off a trap that will then be replaced with who knows what. Stay on your feet until the room plays the 4 mana 7/7 that clears the board when it survives damage; in many cases that will be the only thing that can save you.
  
  Side note: I believe that no trap gets played more than once. That doesn't make it much easier to track, but it's a little something to go on.

Level Six and Seven:

• Blackseed: Instead of evolving minions to something that costs 1 more, now he evolves them into something that costs 3 more. The small advantage you have is that now it costs him a mana to do that, so if he spends all his mana playing minions, you can clear them without him getting to evolve any. If you can get a big enough board lead, his evolves won't matter anymore, but getting to that point is the trick.

• Bristlesnarl: Give this little bastard too long and you'll end up staring down a zoo of giant creatures. Even a board wipe doesn't always help, since it includes stuff like Savannah Highmanes. He carries Deadly Shot and Kill Command, so try to avoid leaving a single big creature out to get merked by that, but otherwise most decks will need to rush him down before his card discounts overwhelm you.

• Candlebeard: Effectively the same as earlier but with more health and the ability to give minions charge for free, which can be an enormous problem for some decks and a trivial one for others (ones with taunts, or secrets that can counter attacks). This is the one battle where having the Cloak of Invisibility can be a major problem for you, as it gives Candlebeard no reason to do anything but smash your face.
  
  Your higher health should counter his ability to apply charge to everything immediately for a while, hopefully long enough to get minions out that he attacks instead of you. Be aware the longer game means it's easier for the board to build to a point where he can play a Sea Giant cheaply, the poison minions will have better targets, and the potential exists for him to dump several cheap cards in one turn and have them all charge. If you have a deck focused around removing threats, as powerful as it is almost everywhere else, there's a good chance you're not going to win this fight.

• Gutmook: This version of Gutmook is far worse than the first. Getting your hand loaded with coins and bananas that will give him a free card every time you use one is bad, and knowing that card, whatever it is, will only cost one, is shit. You really need to rely hard on minion strength and be very judicious in your use of spells, even if your deck is focused around spells. A good deck should have enough minions to handle this fight, but you won't have a lot of room in your hand outside of the junk he piles into it, so a reasonable draw is still needed.

• Lava-Filled Chamber: Don't play anything with two or less health unless you have a specific reason (battlecry/deathrattle effect, to set up a rogue combo, etc). The room's hero power damage only applies to played minions, not summoned ones, so totems and paladin recruits are especially useful here. The room's deck is mostly removal, so it can be useful to play weaker cards to bait out some of the removal before laying out the stuff you want to have survive. Thankfully, the most damage you'll have to do to any single enemy minion to remove it is six (Ragnaros after taking the room damage), so controlling the board isn't too hard for most decks, and if you have that you win—the room will save its damage spells for your minions unless it can finish you off.

• Overseer Mogark: Now that his hero power gives minions five attack instead of two, sometimes it will be correct to clear his deathrattle eggs if you can also deal with the monster that comes out. Always clear any other minion you see. The eggs become doubly problematic with the higher health totals, as he has Brawl in his deck; if you see him early in the run, the game generally ends before Brawl can become a problem, but on level six or seven he can Brawl before you have him near death. If you can efficiently remove whatever minions he puts out, you'll be fine; if not, cross your fingers.

• Pathmaker Hamm: He throws three bombs instead of two at this later level, but apart from the first few turns it's not all that troublesome—you'll often have improved your deck beyond what the extra damage can do to you. The longer games mean more Madder Bombers, though, and if you can't gain a foothold they can combine with Rotface to make your life hell in a hurry. If you keep the board clear, you should naturally win before any of that becomes a problem.

• Voodoomaster Vex: This is a hard fight to give advice on because the way what he plays can affect your deck varies so much. The more helpful battlecries and deathrattles you have in your deck, the more you can take advantage of the double-ups, but that's obvious. He has some questionably chosen cards in his deck, like Bomb Squad, so abuse him if you see them. Otherwise just do your best, and if the fight gives you trouble, try to remember what he does and use that information if you see him again.

• Waxmancer Sturmi: This fight seems much worse than the early version, given that he can copy out full-sized minions for three mana, but his deck doesn't help him much in that respect since only Princess Huhuran, Sylvanas, and Savannah Highmane are going to be huge problems if he drops three-mana versions of them on the board, and he needs eight or nine mana to copy them the same turn he plays them. In this version more than the first, avoid playing anything that will be of greater advantage to him if he copies it than you. He has no AOE except Explosive Trap, so flood the board if you can with 3+ health minions.

Level Eight:

This part of the dungeon has been focused on more in other places, like the Metabomb link above. These are just some ways to mitigate the cheese these bosses throw at you.

• Azari, the Devourer: A pure race, since he burns your deck for two cards every turn. You can't spend too many resources removing his minions, but you also need to take away as much of his ability as you can to get good trades. His only major removal spell is DOOM!, which makes it doubly necessary you do everything possible to keep the game from reaching turn ten. If you're lucky he'll lose at least one to a Doomguard discard. Otherwise it's just a slugfest between his deck and whatever doesn't get burned from yours. If he burns the cards you need to beat him, there's not much you can do about it.

• King Togwaggle: His deck is pretty meh. Play around the fact he has both Evasion and Sudden Betrayal as rogue secrets. Otherwise everything is about his hero power and the treasures he dredges up with it. Thankfully they're not on the level of the stuff that comes from treasure chests, but rather they're the treasures you can pick up along the way for your own deck (which can still wreck your face). Eventually he'll get something great for him and terrible for you, but you don't know what or when, so all you can really do is play a strong game and try to keep resources available in case he hits you with something like a Wand of Disintegration.

• The Darkness: This boss is hell. If you have a lot of small minions, the free minions it gets every turn will run them over, and its Cabal Shadow Priests can steal them too. It has a ton of removal, both single target and board clear. You have three advantages: your deck is bigger; the board clears also wipe out the Darkness' minions, including the one played that turn; and the boss can only hurt you with minions.
  
  More than likely you'll need huge minions that can trade better than 1-for-1 with the Darkness spawns. Jade is very good for this, as long as you can live long enough to get them to 5/5 and above. Hand buff decks are good. Having the +1/+1 passive is great, two of them even more so; it's so good that the existence of this boss makes taking that passive almost automatic if you see it. If you have stealth, you can control the trades, but the same idea holds—even if you try to aggro down the boss, your minions still have to be pretty big to do that before the board wipes come into play.

• Vustrasz the Ancient: The obvious part of this fight is that if you kill a chest, Vustrasz will start damaging you and your board each turn. Less obvious is that if you keep the chests alive, it leaves less space for him to play minions that are usually more dangerous. The buffed chests aren't that problematic either, in terms of the damage they deal; Velen's Chosen can be a pain with the buff to spell damage. There's a limit to that, of course; if one of them gets to be 11/18, you're probably better off finding a way to kill it.
  
  Here's a fun fact, though: Vustrasz's hero power damage is based on how many chests are on the board. It's five minus the number of chests. Thus, if you get rid of a chest through something like Recycle, he'll still start doing damage because the chest is missing. However, this also means that if you have Marin the Fox, the chest he creates will replace one of Vustrasz's. If you killed a chest, or kill one after playing Marin, Vustrasz won't do any damage to you because he still has five chests.

• Xol the Unscathed: You have two main things to deal with: her warlock quest and her beams. I've seen people say they got her to discard the quest somehow, but I've only ever seen her play it on turn one, so it must be with a lucky Orb of Destruction or something. Assuming she has the quest running, she's almost guaranteed to finish it at some point. Try to keep the Howlfiends from discarding multiple cards; killing them in one shot is fine, but if you have hard removal that can kill them without doing damage, that's even better. If you have board control when she plays the portal, the imps are generally manageable.
  
  The challenge of the beams is to track what she has and play around it, including keeping track of her discarded beams so you're not playing around a threat that isn't there anymore. The connection between what she says and the beam she gets is:
  
  Fatality: Destroy all damaged enemy minions.
  Fatigue: Destroy one of your mana crystals.
  Fear: Return a random enemy minion to your opponent's deck.
  Flame: Deal two damage to all enemy minions.
  Flummox: Gain control of a random enemy minion.
  Frost: Freeze a random enemy minion and the minions next to it.
  
  Certain combos are obviously bad news. If she has Flame and Fatality together, you might want to smack a Howlfiend to try and get one discarded if you have a strong board. Flummox is extremely dangerous early, in the turns where you're probably only playing one minion at a time. Waiting until you can play something less dangerous into the beam leaves you open to her zoo, which gets pretty strong even if she's not stealing your minions. Getting your board to a point where you can play around the beams is possible, just get the win before Deathwing comes and fucks up your business.

Treasures

All treasure selections need to be made in consideration of the deck you're building or aiming for (if it's early). Sometimes a generally less good treasure is correct depending on what your deck is doing. That said, some things are plainly better than others. For the most part, this means taking consistent benefits over ones that have big potential but require you to highroll in some way. (The order of the items is in order of personal preference, but things in the same group are relatively close together.)

• Must take: 
• Captured Flag. Rare is the deck that doesn't benefit enough from +1/+1 to all minions that something else is preferable. The only time you might not want this is if it's very late in the run and you've wound up with a spectacularly spell-heavy deck, and even then there needs to be something else pretty good available.
• Cloak of Invisibility. This is just about as good as Captured Flag unless you've already taken a large number of taunt minions. You don't know what you're going to face, minions are the most consistently useful resource available to you, and being able to control trades with stealth is the strongest way to use them. 
• Crystal Gem. Starting with one extra mana crystal means by turn ten, you've had ten extra mana available to you. That's a ton as long as you're using it efficiently, and being able to hero power immediately means you'll never waste a turn no matter the draw (unless you're priest). Less useful if you already have Justicar's Ring, but not by much.

• Usually take: 
• Justicar's Ring. Pretty much every class benefits from an improved, cheaper hero power; the only downside is that if a deck curves well, you won't use it as much. Less useful if you already have the Crystal Gem.
• Shifting Hourglass. Normally I wouldn't consider something you have to draw to be hyper important, but the Hourglass starts being very good around the halfway mark, which is when you start to need it, and decks should be built for the end of runs.
• Wondrous Wand. The Wand is nearly guaranteed to give you a substantial discount and sometimes an enormous one; it ranges from good to game-breaking.

• Often take: 
• Archmage Staff. Few mage spells are downright useless, especially when they don't take up a slot in your deck, so getting one for free every turn out of a zero-mana weapon is fantastic. It can get in the way for weapon users, however, and there are times when you burn a draw from having too many cards. 
• Embers of Ragnaros. The Embers are a cheap way to clear at least two things off the enemy's board, but even better, if you've already cleared the board it's 24 damage to the face. Because it's cheap, it can work on the same turn as some major board clears (e.g. Psychic Scream) to finish an enemy.
• Scepter of Summoning. The Scepter is very good in the right deck, and sometimes the strongest pick regardless, but it somewhat needs the deck to be built around it to be truly effective. This item has the lowest floor in the group, as it's possible to end up without many minions that take great advantage of it, but when your deck is stacked with big things it's insane.
• Glyph of Warding. Completely broken against bosses dependent on playing minions, but less helpful or useless against some of the hardest challenges. If you reach a point where end bosses and encounters like the Trapped Room are the only things that give you trouble, bump this down the list.
• Wish. An absolutely bonkers spell that can save your ass, but you have to get to turn ten first and it doesn't do anything to the enemy's board. 
• Potion of Vitality. Hero health isn't usually the most important thing, but late in a dungeon run, the health boost can swing matches by letting you play much more aggressively. It's also helpful because many of the bosses make bad decisions in going face rather than trading.
• Gloves of Mugging. Can badly screw up some bosses, but others don't care at all. At worst it's not especially useful, but as an early game draw it's so good at wrecking what many bosses can do, and it makes a solid top deck as well. Doesn't rate higher because several bosses have junk in their decks, but even then you're taking away something, so it's never bad. 

• Sometimes take: 
• Robe of the Magi. Holy shit-level power on damage spells, especially AOE that only hits the enemy board, but you rarely have enough of these for the Robe to give you a major advantage.
• Wand of Disintegration. Incredibly powerful one time, but too often the bosses you use it against can refill the board. Really good sometimes, not nearly as good as you want it to be at others, assuming you draw into it at all.
• Magic Mirror. Bump this up if you have the option to take it when you already have several minions in the deck you'd like to copy. Otherwise it relies on the hope you'll draw both the Mirror and something you want another copy of, because not every boss has something you'll want in their deck.
• Boots of Haste. Never really as good as A.F. Kay makes it look, and maybe the worst top deck of any treasure, but the bananas potential makes it worth taking if there aren't any better options.
• Horn of Cenarius. Move this up if you already have a very recruit-friendly deck. At minimum, however, you have the beginner minions that might get recruited, and not many decks carry lots of big minions without the Scepter of Summoning, which makes the recruit function a little less useful (though still very good).
• Golden Kobold. It's pretty nice to see when you get it out of a treasure chest, but that's because it lands directly in your hand. In this case, you're taking it as something you have to draw, which makes it less good. But it can still save a bad hand, and it's a 6/6 taunt for three mana, so it's never a terrible pick.
• Vorpal Dagger. Can get you out of trouble in a hurry, save your board for a little while, and if you're a druid, going face with it to finish someone off is more of an option. Can get in the way of other weapons. More flashy than consistently effective—not that many bosses are liable to overwhelm you with minions, although that number includes all of the end bosses.
• Khadgar's Scrying Orb. A huge boost to a spell-heavy deck, but not that many decks will be spell-heavy enough to use it well. More valuable if it's offered late and you already have a deck that can abuse it.
• Totem of the Dead. Incredible with a lot of deathrattle cards, but if it's offered early, it's very hard to expect that you'll have enough of those cards to make it worthwhile. The value of this goes way, way up in hunter.
• Battle Totem. The flip side of Totem of the Dead. It's a little easier to abuse battlecry cards since the effect happens right away, but this goes lower on the list because the battlecry bucket is in shaman and it just isn't as good as hunter deathrattle.
• Loyal Sidekick. Like the Shifting Hourglass, this becomes more useful the later you go. It's not anywhere near as powerful as an extra turn, though. But a cheap, gigantic minion is always nice to have, and as a bonus, if Waxmancer Sturmi tries to copy him, the copy self-destructs.
• Orb of Destruction. Removing two mana crystals is usually more helpful than the discards, but you have to draw it early for the crystal destruction to be of maximum use. Like the Glyph of Warding, this can absolutely dominate earlier bosses, but later bosses have enough tricks that you really need it at or near the beginning of the game for it to be of maximum use.

• Rarely take: 
• Amulet of Domination. Better than Magic Mirror in that it steals a minion rather than just copying one, but you may not have an option you'd want in your deck.
• Bag of Stuffing. Occasionally fantastic, but you spend most of the game with a deck you don't want to draw a ton of cards from at once due to fatigue. Can let you keep a ton more cards against Azari, albeit at the cost of fatiguing much faster.
• Mysterious Tome. Six mana worth of secrets at the start of the game for free is pretty good, but pretty good isn't much compared to what many of the treasures do. They're rarely bad and rarely incredible.
• Party Portal. Much better if you already have the Cloak of Invisibility and some big spells (although even small ones are fine—free minions are free minions). Basically useless without stealth.
• Bag of Coins. Lets you play an extra card or two. Useful but not overwhelming.
• Wax Rager. Instant resummon makes this a better deathrattle than Dreadsteed, and during most of the run it can seem incredible. But it's usually terrible against the final boss; Xol can steal it, The Darkness can Entomb it, Togwaggle can get a treasure that either silences and destroys it or steals it, Azari can burn it, and Vustrasz... might be good against Vustrasz. The fact it can be so dangerous in other fights keeps it off the bottom level.
• Small Backpacks. Two free cards. Sweet. Not that sweet.
• THE CANDLE. A replayable 1-mana Flamestrike should be more useful than this. If your deck is strong, you just don't wind up needing this very often, and plenty of other treasures help to put you in that position.
• Mask of Mimicry. Needs just the right situation to work. Helps if you have bad cards, which hopefully you don't.

• Take only as a flier: 
• Blade of Quel'Delar, Hilt of Quel'Delar. The weapon you get if you finish the sword is nuts, but it's almost impossible to get both pieces. Maybe if you end up in the Treasure Vault, but even then you'll probably have needed to get one piece earlier, and on their own you'll almost always have a better option.
  
  Basically, it's only worth taking one if the other two options are worse.

• Avoid: 
• Rod of Roasting. Not a totally unreasonable choice if you have the Potion of Vitality, and maybe ok if you're not confident you can beat the last boss in a straight up fight, but basically not good. If you get to turn ten and it's the only way you have to win, you're probably behind and more likely to lose anyway when you use it.
• Portable Ice Wall. Quite a good blocker if the opponent can't remove it, but too many of them can, especially late in the run. If they steal or copy it, that's even worse. A 3/15 taunt that could attack might have some consistent value, but this is best in fights you shouldn't have trouble winning anyway.
• Greedy Pickaxe. It's only good if you get it in the first few turns and don't already have a weapon worth using. Yes, the mana crystals are very good when it works out, but that's far too rare to waste a pick on this.
• Primordial Wand. Can theoretically take a board weaker than your opponent's and turn it around, but you're usually either winning or don't have much to adapt. The ultimate win-more card, and surprisingly expensive at four mana given how cheap some of the other treasures are to cast.
• Portable Forge. A weapon for one mana is almost like freerolling, but so many legendary weapons are useless (or useless for certain classes) that almost any other treasure is more likely to be helpful.
• Grommash's Armguards. Most decks don't have the weapons to really abuse this, and you have to draw the weapons to abuse it on top of that.
• Dr. Boom's Boombox. Funny, a good amount of total damage, but mostly uncontrollable.
• Scroll of Confusion. Maybe you get the right spell at the right time. Probably you don't.
• Aleatoric Cube. Destroy your deck for a discount on whatever you end up with. Defeats the entire purpose of building your deck carefully, plus a lot of bosses have cards that are simply weaker overall than yours.